Unrecognised Gedcom tag: FREE

I'm trying to use a gedcom file that has a lot of occurrences of an 
unrecognised tag "FREE" at the 1 level under INDI (one per INDI). It 
typically occurs in association with BIRT and DEAT. Problem is I can't 
figure out what it means and the rest of the data doesn't help either. 
The main data seems to be a date. Can anyone shed light on this tag.
Thanks
Peter